Re: Where I find Bessel function for Ada ?

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Wed, 26 Nov 2008 08:12:21 -0800 (PST), Ludovic Brenta wrote:

> On Nov 26, 4:09 pm, Ken Thomas <k...@ecs.soton.ac.uk> wrote:

>> As the code for bessj0 is very short, translation to Ada is a small
>> exercise. On the other hand, the code seems to deal with only single
>> precision arithmetic so does not promise high accuracy.
> 
> I suppose this is easy to fix by making the Ada implementation
> generic. The user then instantiates it for any floating-point type
> with the required accuracy.

An ability to do so depends on the accuracy of the constants used in the
implementation.

A good-designed library should have the accuracy of the result within n *
T'Model_Epsilon or, better, within the range f(x)'Pred..f(x)'Succ. It is
non-trivial to do for a generic package. Short types will suffer accuracy
losses due to insufficient precision. Long precision types will due to
inaccuracy of the coefficients. Most likely in a generic body you will need
some "carrier" type of the precision higher than of the argument type. In
some cases T'Base can help. In others it cannot...

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de